bio11fandomcom-20200216-history
Diversity of Living Things
taxonomy (classificatoin, naming, evidence for relatedness, dichotomous/heirarchical classification systems) *biodiversity (importance, impact on humans) *"tour of the kingdoms" (viruses, bacteria, fungi, protists) - characteristics and structure-function relationships = Identifying, Naming, and Classifying = Species Concepts * Morphological species concept focuses on the morphology (structure) -- relatively simple to use, common for plants * Biological species concept focuses on reproduction -- can two species mate and produce viable offspring in nature? * Phylogenetic species concept focuses on evolutionary relationships -- useful for bacteria, but hard to discern Naming species * binomial nomenclature: two part scientific name for each specie * two names, first of genus, second of species * italicized, first name capitalized Taxonomic Classification of Species *A rank is a taxonomic category *A taxon is an instance of a rank This chart shows an example of the taxons for the grey wolf. = Determining How Species are Related = *Modern classification aims to organize species according to their evolutionary relatedness *In general, organisms with more taxons in common share a more recent common ancestor Evidence of Relationships Anatomical Evidence *using body size, shape, and other physical features (anatomy, a branch of morphology) *ex. dinosaurs, birds, and Archaeopteryx *'homologous structures' are excellent evidence *ex. whale, bat, horse, human arm bones Physiological Evidence *using functioning of organisms (including enzyme and protein structure) *ex. Guinea pigs have their own order since their proteins are very different than that of rodents DNA Evidence *Comparing genetic sequences *ex. Fungi have been shown to be closer to animals than to plants Phylogenetic Trees *show evolutionary relationships *consist of a variety of branches *each branching point has exactly two branches coming out of it = Dichotomous Keys = *more useful for classifying organisms "in the field" *based on "yes/no" decisions *based on ease of classification, not evolutionary significance = Kingdoms and Domains = *There are two domains and six kingdoms to which all organisms belong Bacteria Morphology *very similar to archaea *have prokaryotic cells (no nucleus) *circular DNA, not bound by membrane (single chromosome) *no organelles *unicellular only Physiology *cell walls made of peptidoglycan *autotrophic and heterotrophic *asexual reproduction through binary fission *many are anaerobic Archaea *very similar structurally and physiologically, but very different biochemically than bacteria Morphology *very similar to bacteria *have prokaryotic cells (no nucleus) *circular DNA, not bound by membrane (single chromosome) *no organelles *unicellular only Physiology *cell walls not made of peptidoglycan (may not have cell wall) *autotrophic and heterotrophic *asexual reproduction through binary fission *many are anaerobic Eukarya *have eukaryotic cells (have a nucleus) *uni- and multicellular *most are aerobic Protista *catch-all category; main unification is difficulty of classification *uni- and multicellular *cell wall (if present) made of cellulose *autotrophic and heterotrophic *asexual (through mitosis) and sexual reproduction Plantae *multicellular *cell wall made of cellulose *autotrophic *sexual reproduction Fungi *mostly multicellular *cell wall made of chitin *heterotrophic *sexual reproduction Animalia *multicellular *no cell wall *heterotrophic *sexual reproduction Viruses *not a domain/kingdom *not classified as living organisms *consist of DNA/RNA content and capsid protein coat *reproduce by invading host cell through the lytic or lyxogenic cycle Structure *head *tail *nucleic acid core (contains genetic material DNA/RNA) *capsid covers DNA content (head + tail) *animal viruses look like balls *plant viruses look cylinders with a "spring" *bacterial viruses look like a lunar lander Lytic cycle #virus attaches itself to cell membrane #injects genetic material and enzymes into host cell #viral enzymes degrade host cell DNA #host ribosomes produce new viral proteins #new viruses are assembled #cell lysis (breaks open), killing the host cell Lysogenic cycle *used by retroviruses and other viruses #virus attaches itself to cell membrane #inject genetic material and enzymes #'Recombination': viral nucleic acid is inserted into host DNA #Virus becomes a provirus: the incorporated viral DNA #Host cell division occurs (provirus now have many copies) #enzymes degrade host DNA #new viruses are assembled #lysis Retroviruses *contain an enzyme called reverse transcriptase and RNA instead of DNA *reverse transcriptase uses viral RNA to make DNA that becomes incorporated into host's DNA *lytic and lysogenic cycles are both involved *does not destroy cell immediately -- instead, the provirus directs the cell to make new viral proteins = Classifying Types of Biodiversity = Species Diversity *the the variety of species in a given area *leads to better resilience (the ability to adapt to change and disturbances) Genetic Diversity *the variety of inherited traits within a species *gene pool is the genetic diversity within a population *genetic diversity can provide resistance to disease (and lack of can cause disease) *ex. Tasmanian devils are endangered, with little genetic diversity, so suffer from mouth cancer Ecosystem Diversity *the rich diversity of ecosystems on Earth *important since different ecosystems provide different ecosystem services (like water filtration, food production, climate regulation, etc)